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This video segment adapted from FRONTLINE: “Poisoned Waters” discusses the PCB cleanup of South Park, a Seattle neighborhood along the Duwamish River. In 2004, the community learned that some of its streets and yards were contaminated with toxic chemicals called PCBs. Citizens, galvanized by the finding, demanded the long-promised cleanup of an abandoned asphalt plant. The proposed cleanup led to a debate, when the Port of Seattle promised to reduce PCBs to the EPA standard of 25 parts per million (ppm), but residents demanded a stricter standard of 1 ppm. After debate, the city agreed to the stricter standard.
Download and SharePCBs are a class of toxic chemicals that belong to a family of synthetic chemicals called chlorinated hydrocarbons. PCBs come in different consistencies and colors, from light-colored liquids to black, waxy solids; they are chemically stable, flame resistant, and good electrical insulators. For these reasons, PCBs were used in a wide range of industrial and commercial applications in the United States until 1979, when Congress banned their manufacture.
PCBs have been shown to cause cancer in animals and have been associated with specific kinds of cancer in humans, such as cancer of the liver. In addition, animal and human studies indicate that PCBs also likely cause a number of other health problems, such as damage to the immune, reproductive, endocrine, and nervous systems. For example, studies have shown that pregnant women who were exposed to relatively high levels of PCBs had babies with problems such as low birth weight and impaired motor skills.
People can be exposed to PCBs by consuming contaminated food and water and by breathing contaminated air. PCBs can accumulate in plants and animals, which may then be eaten by people. PCBs enter the food chain after they get taken up by small organisms that absorb them from the air and water. Furthermore, PCBs are lipophilic, meaning that they have an affinity for fat and accumulate in fatty tissues and organs. As a result, species at higher levels on the food chain can have high levels of contaminants because of the process of biomagnification. A major source of PCBs comes from ingesting contaminated fish.
PCBs are released into the environment through their manufacture as well as use. In addition, improper disposal of PCB waste and poorly maintained hazardous waste facilities may still be causing PCB pollution even long after their ban. Because they are very stable compounds that do not degrade easily, once they enter the environment, they can remain there for long periods of time. PCBs persist and circulate in the environment and can be carried long distances. As a consequence, PCBs are found all over the world and may end up far from where they were originally released.
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